Tính: c) ( 1/2 + 1/3 )^2 : ( 1(1/2 ) ^2

c) ${(\frac{1}{2}+\frac{1}{3})}^2:{\left(1\frac{1}{2}\right)}^2={\left(\frac{5}{6}\right)}^2:{\left(\frac{3}{2}\right)}^2$

$=\frac{5^2}{6^2}:\frac{3^2}{2^2}=\frac{5^2}{6^2}.\frac{2^2}{3^2}$

$=\frac{5^2{.2}^2}{2^2{.3}^2{.3}^2}=\frac{5^2}{3^4}=\frac{25}{81}$